Dust collection system

ABSTRACT

A dust collection system for portable sanding or grinding equipment employs a cyclone separator mounted directly on the tool or machine, with a dust outlet duct at the narrow lower end of the cyclone, and a cartridge air filter mounted on the top of the cyclone. The filter returns the air flow from the machine to the ambient air in the vicinity of the tool. The dust is concentrated in the cyclone, and a small volume air flow then moves the dust through an elongated flexible hose or duct to a remote dust collection station. An air pump at the remote dust collection station provides sufficient air flow to draw the small volume of air plus entrained dust from the tool-mounted cyclonic separator. A cyclonic separator at the remote station separates this dust from the air flow and deposits it in a collection tank or drum.

BACKGROUND OF THE INVENTION

This invention is directed to devices and equipment for removing processdust coming from a dust generating machine, such as a sanding machine,and separating the dust from exhaust air flowing from the machine. Theinvention is more specifically directed to a compact and efficientsystem for removing the production dust from the work area to a dustcollection station located beyond the work area, and which removes amajority of the air from the dust flow.

For many types of machines for processing a workpiece, some means has tobe provided to dispense with the grindings, chips, and particulatematter that is generated by the machine during operation. For example,in the case of wood working machines, such as sanders, joiners, and thelike, wood that is removed from a workpiece has to be collected andremoved from the work area so as to avoid either a breathing hazard forthe workman or a fire hazard. More specifically, in the case of portableequipment, such as floor sanders and edgers, it is conventional to drawoff the dust that is generated by the machines and then send the airthat is carrying the dust into a filter bag arrangement. An alternativetechnique is to attach a flexible hose or conduit to the dust outletduct of the machine, and pump the air in the conduit, plus the entraineddust, to a collection station outside. For hand-held and mobile powertools, such as floor sanding equipment, the associated dust collectionsystems currently in use are cumbersome, impractical, or inadequate.

Two systems are currently in use. In one system, a blower on the machineis used to extract dust from the sanding or cutting operation, and theair and entrained dust go into a filter to collect the dust and filterthe air. Work operations have to be suspended frequently to clean thefilter and dispose of the collected dust. These maintenance-intensesystems blind or clog readily, which reduces the pickup volume at thesource, allowing the particulate waste to become airborne or tointerfere with the operation. In the second system a flexible hoseconnects the unit to an external dust collection unit which draws thewaste from the tool. These systems do not deliver the necessary airvolume to the tool because of intrinsic mechanical problems ofdelivering air through the extended lengths of flexible tubing. Hugeenergy requirements and high air velocities are necessary to overcomefrictional losses. Frictional losses in ducts increase exponentiallywith area velocity, so very wide diameter tubing is used, and thisrelatively large tubing, being quite cumbersome, hinders the operator inusing the machine.

The system of long flexible hoses for collecting dust from portable woodsanding machines generally require a combination of a number ofdifferent hoses of various diameters, and a series of air pumps andblowers to maintain a satisfactory air draw. In addition, because all ofthe air that exits the sanding machine has to be carried all the way outto a remote collection station, the flexible hoses are required to havea rather large diameter.

A filter bag that is carried on the portable sanding machine isgenerally not satisfactory for a number of reasons. First, the bags areeither too porous and do not remove enough particulates from the air, orare too fine and tend to clog after a period of operation, choking offthe flow of exhaust air from the machine. Also, the bag collectionsystem concentrates the fine particulates of a combustible material(wood dust), and this dust can ignite if a spark or heated material fromthe sanding operation lands in the bag. Such a situation can produce anexplosion, and thus exposes the worker to an unnecessary danger.

A number of cyclonic separators have been proposed, typically forseparating particulate matter, such as grain, powders, or dust, from aflow of air. However, to date, no one has proposed or consideredmounting a cyclonic separator on a portable sander or other dustgenerating device so as to concentrate the dust and allow a smaller airflow, and a smaller conduit, to be used is moving the dust to the remotedust collection station.

OBJECTS AND SUMMARY OF THE INVENTION

Accordingly, it is an object of this invention to provide a highlyenergy efficient cyclonic separator-based dust collection system thatavoids the drawbacks of the prior art.

It is a more specific object to provide a dust collection system inwhich the air pressure drop is dramatically reduced as compared withprior art dust collection systems.

It is a further object of this invention to provide a dust collectionsystem in which a majority of the separation of dust from the exhaustair and the filtering of the exhaust air are carried out at thedust-generating machine or tool.

It is another object to provide dust collection system which reduces thepower requirement, and also reduces the inherent fire or explosionhazard of the dust collection equipment.

According to an aspect of the invention, a compact and efficient dustcollection system is provided for collecting production dust from afloor sander or other source machine that generates such dust in aproduction operation. The source machine has an internal blower forpicking up the dust that the machine generates and exhausting the dust,entrained in a stream of air, to an exhaust outlet on the sourcemachine. A compact, low-volume cyclonic separator is mounted on thesource machine. The cyclonic separator has an inlet portion at the top,and an inner tubular baffle coaxial with the upper inlet portion andhaving open ends. The inlet portion and inner baffle define between theman annular inlet space. A frustoconic portion beneath the upper inletportion and having a wide end joined at the inlet portion and thisdescends to a narrow lower end, where there is a dust outlet duct. Aninlet duct receives the air flow and exhaust dust from the machine andinjects this air flow into the annular inlet space. a pleated airfilter, or equivalent air cleaning means, is situated above cyclonicseparator for cleaning air that passes out through the tubular baffle.This permits the filtered clean air to return into the ambient air inthe vicinity of the source machine. The dust is then concentrated at thebottom of the cyclonic separator. An elongated flexible duct or hose iscoupled from the dust outlet duct of the cyclonic separator to a dustcollection station positioned remote from said source machine. Becausethe dust is concentrated in the cyclonic separator, the air flow orvolume required for conveying the dust to the dust collection station isreduced by a factor of between five and ten as compared with the systemsdiscussed previously. This is because the secondary air flow between theseparator and the dust collection station is used only for moving thepreseparated dust, and does not have to supply the correspondinglygreater air volume that is required to extract the waste dust from thecutting operation at the tool. Because the secondary air flow is reducedso greatly, a much smaller diameter hose can be used, typically ¾ inchto 1 inch. This tubing can be bundled with the electric cord for thetool, and thus will not interfere with operation of the sander or othertool.

In a preferred embodiment, a rigid hollow conduit both serves as thetubing connecting the outlet of the machine to the cyclonic separatorand as the means for supporting the cyclone separator on the machine.

The system can be run at a lower power requirement, e.g., at 110 volts,which is an advantage in that many non-commercial locations do not have220 volts or three-phase power. The operator can continue to workwithout interruption, as the dust is carried to a much larger receptacleat the dust collection station. There is increased fire safety, as theheat and sparks that can result from the grinding or sanding operationare far from the dust storage location. An improved inlet port for thecyclonic separator permits superior dust pickup and better separationwith less back pressure resulting from the separation. Industrialhygiene is vastly improved.

-   -   a second cyclonic separator can be used at the outside dust        collection station, separating the dust from the incoming air        flow, and dropping the dust from the nose of the cyclonic        separator into a drum or similar receptacle.

The above and many other objects features, and advantages of thisinvention will become apparent from the ensuing detailed description ofthe preferred embodiments, which is illustrated in the accompanyingDrawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective system view of a dust collection system for afloor sander and an edger, according to one embodiment of thisinvention.

FIG. 2 is an assembly perspective view of the cyclonic separator that ismounted onto the floor sander, according to this embodiment.

FIG. 3 is a top view of the barrel of the cyclonic separator of FIG. 2.

FIG. 4 is a schematic elevation showing flow of air and waste for thecyclonic separator of FIG. 2.

FIG. 5 is a perspective view of the cyclonic separator that is mountedonto the edger machine according to this embodiment.

FIG. 6 shows the cyclonic separator of FIG. 5 with filter cartridgeremoved, and with some hidden elements illustrated in dash lines.

FIG. 7 shows the cyclonic separator that is mounted onto the collectiondrum at the dust collection station according to this embodiment.

FIG. 8 is a top view of the cyclonic separator of FIG. 7.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Now with reference to the Drawing, FIG. 1 shows a dust collection systemaccording to an embodiment of this invention in which dust is separatedfrom the air flow at the tool or machine, with the air being cleaned andreturned to the ambient in the vicinity of the tool and with the dustbeing transported on a smaller volume air flow to a remote collectionsite.

A dust generating machine or tool, here a floor sanding machine 12, hasa built-in exhaust blower 14 that vacuums up any sanding dust producedand discharges it upwards through an upright pipe 16. Aninlet-connection ell 18 is mounted at a top end of the pipe 16, and acompact cyclonic separator 20 is supported on the ell 18. In thisembodiment, the cyclonic separator 20 has a barrel or drum 22 at itsupper end. The cyclonic separator can be described with additionalreference to FIGS. 2, 3, and 4. An inlet pipe 24 that fits into the ell18 extends though the barrel 22, as will be discussed later. a tubularbaffle 26, which has open upper and lower end, is disposed coaxiallywithin the separator barrel 22. This baffle 26 can be cylindrical insome cases, and here has a tapered, frustoconic shape. An upper annularplate 28 closes off the top of the barrel 22, with the baffle 26extending to or penetrating through a central opening in this plate 28.The baffle 26 and barrel 22 define between them an inlet space 30beneath the upper plate. A distal end 32 of the inlet pipe 24 protrudesinto a central portion of this inlet space 30, and this geometry reducesturbulence and back pressure at this point, providing a more efficientair flow.

A frustoconic cyclone portion 34 has a wide, upper mouth joined to thebarrel 22, and the cyclone portion 34 tapers downward to a smalleropening at its nose, where a dust cup 36 collects the sanding dust thatis separated from the spiraling internal air flow. An dust outlet pipeor exhaust pipe 38 protrudes from the dust cup 36, and an elongatedflexible hose or conduit 40 (see FIG. 1) carries off the sanding dust ina small-volume air flow to an outside remote dust collection station 42.The dust collection station will be discussed later.

An air filter assembly 44 positioned atop the cyclonic separator 20filters the air that flows from the sanding machine 12 and through theseparator 20, and returns the filtered air back to the ambient space. Asshown in FIGS. 2 and 3, this assembly includes a vertical threaded post46 mounted on a brace 48 across the mouth of the internal baffle 26,which extends upwards above the plate 28 along the vertical axis of theseparator 20. a pleated cylindrical filter cartridge 50 is positionedhere and held in place on the post 46 using a washer 60 and thumb nut62.

In this embodiment, an upper portion 64 of the baffle 26 protrudes abovethe annular plate 28, forming a cylindrical flange that fits into acircular opening (not shown) in the base of the cartridge 50.

FIGS. 3 and 4 illustrate the air flow through the cyclonic separator 20.The air enter via the inlet pipe 24 into the space 30, and then proceedson a downward spiral path towards the dust cup 36 and the lower nose ofthe cyclone 34. The sanding dust remains in the cup, and the airflowproceeds upwards along the axis or core, through the baffle 26, and outthrough the filter assembly 44. The cyclonic separator presents only asmall back pressure to the exhaust blower 14 on the machine 12, and onlya minor air flow volume, provided as a suction or draw from the remotedust collection station 42, is needed to move the concentrated dust fromthe dust cup 36 out through the flexible conduit 40. This permits theconduit 40 to be small in diameter, e.g., ¾ inch in most applications,and this is far less cumbersome than the large diameter conduitsrequired by the prior and present remote-collection systems. The powercord for the machine can also be bundled with the flexible conduit 40,which has advantages for the operator.

As also shown in FIG. 1, a second tool can also be provided with acyclonic dust collection system, and in this embodiment, an edge sanderor edging tool 66 is shown. The edger 66 has an internal exhaust blower(not shown), which picks up process dust and blows it through an exhaustpipe 68, here a rigid tubular member that also supports a cyclonicseparator 70. This separator can be of a smaller size than the separator20. An inlet pipe 72 is fitted into the pipe 68 and extends into abarrel 74 of the separator. An inner baffle 76 is disposed coaxial withthe barrel 74. A frustoconic cyclone 78 is joined with the barrel 74 andtapers downwardly terminating at a dust cup 80, from which a dust outletpipe 82 extends. A second flexible small-diameter conduit 41 then leadsfrom the dust cup 80 to the remote collection station 42.

An annular plate 84 closes off the top of the barrel 74, and a supportbracket 86, here formed with two upwardly extending legs, risesvertically above the opening at the center of the plate 84. a post 88with internal female threads is supported on top of the bracket 86. athumb wheel 90, having a male threaded shaft (not shown), is used tosecure a pleated cylindrical filter cartridge 92 in place against thetop of the cyclonic separator 70.

Details of the remote collection station 42 of this embodiment areillustrated in FIG. 1 with additional reference to FIGS. 7 and 8. Here,a cyclonic separator 94 disposed at the remote station is of frustoconicshape, with an inlet pipe 96 that is fed from the conduits 40 and 41with the process dust from the machines 12 and 66. a siamese connectioncan be used here. This separator also has an internal tubular baffle 98,disposed coaxial with the frustoconic separator 94, and having an upperportion that extends above the top of the separator to serve as an airexhaust port. A dust conduit 102 extends downward from a nose of theseparator 94 into a dust collection drum 100 (or other dust storagevessel). In this case a top of the drum 100 has a fitting 104 thatconnects with the dust conduit 102. As shown in the top view of FIG. 8,and upper annular plate 106 closes off the top of the cyclonic separator94, and the inlet pipe 96 protrudes into the middle of the volume thatis defined between the wall of the cyclonic separator 94 and the tubularbaffle 98.

Referring again to FIG. 1, exhaust air from the separator 94 is carriedvia a conduit 108 to a filter unit 110 which removes remainingparticulates in the exhaust air, and thence via another conduit 112 toan air pump 114. The pump provides a draw of vacuum that moves the dust,plus a relatively small flow of air, from the dust cups 36, 80 of theseparators on the two tools, through the elongated flexible conduits 40and 41 to the dust collection station 42, where the air flow continuesthrough the cyclonic separator 94, so that the process dust ends up inthe barrel 100.

Because the dust and exhaust are from the tool are separated out at thecyclone separators 20 and 70, only a small amount of air flow is neededto carry away the dust to the remote dust collection station 42. The airvolume to the tool can be reduced by a factor of between five and tentimes, because it is only used to extract the preseperated waste, and isnot supplying the considerably greater air volume needed to extract thewaste from the cutting or sanding operation.

The independent stand-alone dust collection station 42 downstream of thefilter/separation 20 and 70 contains all the processing waste from theportable processing equipment, which is recovered by means of a smallnegative pressure operating through the cyclone separator 94. The drumor barrel 100 can be provided with a plastic bag liner. As the dustbarrel is at a negative pressure, a vacuum bag hold down feature isemployed, in which a hose 116 extends from the pump 114 to a vacuuminlet fitting 118 on the barrel 100, to maintain a vacuum or negativepressure between the barrel and the plastic bag liner to draw and holdthe bag to the inside of the barrel. The bag can be tied off and liftedout when full, thus eliminating the need to dump. This also keeps theoperators from being exposed to the fines and dust contained in the bag.The independent stand-alone nature of the waste collection drum orbarrel 100 also allows for different size barrels to be interchangedeasily and cost effectively, accommodating the scope of the project andthe volume of waste material to be collected.

The advantages over the prior art dust collection systems can be quicklysummarized as follow: There is a low power/low energy requirement, andthe system can be powered entirely from a 110V single phase supply. Thesmall flexible tubing 40 for carrying the dust from the tools makesmachine operation vastly easier, and the tubing can even be bundled withthe power cord for the tool. The operator does not need to interrupt thesanding, grinding, or finishing process for the purpose of unclogging oremptying bags or filters, or for removing waste bags from the tool ormachine, as the waste material is carried continuously from the tool toa large off-worksite container. There is improved fire safety as anyfriction-induced flame or sparks will not reach the storage location forthe combustible waste materials; that is, the waste collection barrel isfar downstream of the grinding or sanding operation, and is at alocation far from the operator. The high-efficiency cyclone separators,with low pressure drop inlet tubes, provide for superior dust pick up atthe tool, and permit the waste material to be carried off withoutsignificant back pressure. The filter service interval is also verylong, and pressure loss through the filter cartridges is also very low.The filtration of air and separation of dust vastly improves theindustrial hygiene for the operators.

While the invention has been described hereinabove with reference to afew preferred embodiments, it should be apparent that the invention isnot limited to such embodiments. Rather, many variations would beapparent to persons of skill in the art without departing from the scopeand spirit of this invention, as defined in the appended Claims.

1. A dust collection system for collecting production dust from a sourcemachine that generates such dust in a production operation, said sourcemachine having a blower means for picking up said dust and exhaustingthe dust entrained in a stream of air to an exhaust outlet on the sourcemachine; comprising a cyclone separator mounted on said source machine,said cyclone separator including a circular upper inlet portion, aninner tubular baffle coaxial with the upper inlet portion and havingopen ends, the upper inlet portion and inner baffle defining betweenthem an annular inlet space, a frustoconic portion beneath the upperinlet portion and having a wide end joined to the upper inlet portionand a narrow lower end, a dust outlet duct at said narrow lower end, andinlet duct extending from outside the upper inlet portion into saidannular inlet space; air cleaning means above upper inlet portion forcleaning air that passes out through said inner tubular baffle andpermitting the air to return into ambient air in the vicinity of saidsource machine; a first conduit coupled between the exhaust outlet onthe source machine and the inlet duct of the cyclone separator; and anelongated flexible duct coupled from said dust outlet duct to a dustcollection station positioned remote from said source machine, forconveying a minor flow of air plus dust entrained therein to the dustcollection station.
 2. A dust collection system according to claim 1wherein said air cleaning means includes a replaceable air filterremovable positioned above said outer cylinder.
 3. A dust collectionsystem according to claim 2 wherein said air filter is in the form of acylinder mounted coaxially with said cyclone separator.
 4. A dustcollection system according to claim 1 wherein said inlet ductpenetrates to a region of said annular inlet space that is midwaybetween said upper inlet portion and said inner tubular baffle.
 5. Adust collection system according to claim 1 wherein said first conduitis a rigid hollow member forming means for supporting said cycloneseparator on said source machine.
 6. A dust collection system accordingto claim 1 wherein said inlet portion and said tubular baffle are in theform of coaxial cylinders.
 7. A dust collection system according toclaim 3 further comprising a threaded post extending upward at an axialof said tubular baffle and above said cyclone separator, and femalethreaded means for holding said filter in place on said threaded post.8. A dust collection system according to claim 1 wherein said dustcollection station includes a second cyclone separator having an inletport to which said elongated flexible duct is connected, a dustcollection drum positioned below a lower end of said second cycloneseparator for receiving the dust carried to it through said elongatedflexible duct, an a pump for drawing air through said second cycloneseparator, and an air filter interposed between an outlet baffle of saidsecond cyclone separator and said air pump.
 9. A dust collection systemaccording to claim 1 wherein said elongated flexible conduit is a hoseof about ¾ inch to one inch in diameter.
 10. Portable independentstand-alone cyclonic dust collection station adapted to receiveproduction dust from a dust-creating tool via an elongated flexibleconduit that carries off the production dust from said tool to an inletpipe of the dust collection station; the dust collection stationcomprising a. a frustoconic cyclonic separator having a wall that is atleast partly conic, said inlet pipe penetrating said wall; b. a dustcollection drum disposed beneath said separator; c. a fitting connectinga lower nose of said cyclonic separator to said drum and closing off anupper side of said drum; d. an internal tubular air baffle disposedcoaxially within the cyclonic separator and having an exhaust portleading from an upper end of said cyclonic separator; f. an exhaustconduit extending from said exhaust port of said tubular air baffle; g.filter means having an inlet pipe connected to said exhaust conduit forcatching particles passing out of said exhaust baffle, and having anoutlet; and h. an air pump having an intake connected to the outlet ofsaid filter unit and an exhaust for discharging cleaned, filtered, anddust-free air into the ambient.
 11. Portable independent stand-alonecyclonic dust collection station according to claim 10 in which saidfilter unit and said air pump are mounted on a wheeled hand truck. 12.Portable independent stand-alone cyclonic dust collection stationaccording to claim 10 in which said dust collection station is poweredby a 110 volt single-phrase motor.
 13. Portable independent stand-alonecyclonic dust collection station according to claim 10 wherein saidvacuum drum is provided with a plastic bag liner.
 14. Portableindependent stand-alone cyclonic dust collection station according toclaim 13 further comprising a vacuum hold-down arrangement whichincludes a vacuum inlet fitting on said drum, the hold-down arrangementdrawing and holding the bag liner to the inside of drum.
 15. Portableindependent stand-alone cyclonic dust collection station according toclaim 10 , wherein said cyclonic separator has a frustoconic side wall,with said inlet pipe penetrating the frustoconic side wall.